DxOMark measurements for lenses and camera sensors

Do lenses affect light transmission?

Photographic lenses are made of several elements of very pure glass, each element being carefully coated to limit reflection. However, a portion of the light is lost in the optical system due to residual reflection and absorption.

The transmission factor (the proportion of light that actually makes its way to the sensor) depends on the optical formula (the number of lenses, the glass and coating formulas) and to a lesser degree on the shooting parameters.

As a measure of transmission, DxOMark reports the T-stop, defined as the f-number of a lens with 100% perfect transmission, and resulting in the same illumination of the sensor at the image center as the lens to be measured.

What does DxOMark report for transmission (T-stop)?

DxOMark displays T-stop at full aperture function of focal length, and transmission loss at full aperture function of focal length.

Further readings for the DxOMark measurements for lenses and camera sensors

To provide photographers with a broader perspective about mobiles, lenses and cameras, here are links to articles, reviews, and analyses of photographic equipment produced by DxOMark, renown websites, magazines or blogs.

On DxOMark, we evaluate and rank many types of digital cameras with image sensors that vary widely in pixel count, pixel size, and digital signal processing. To ensure that sensor performance comparisons between cameras are fair, it is very important both to test under identical shooting conditions and to take viewing conditions into account.

The Nikon D5000 and the Canon EOS 500D were two main releases for spring 2009. Launched at the same time, and targeting the same market, these two cameras were the perfect subjects to use for an extensive demonstration of the DxOMark Database.